CodePen is a JavaScript, HTML and CSS code editor that packs an instant preview. It also also works in a browser which means, in an instant, you can test and admire share your creations. CodePen is also a great place to practice your Sass, peruse other coders and share your work!

Despite its name, CSS Tricks - created and maintained by Chris Coyier - is also a great place to learn about Sass. It's also well worth checking out the site's Shop Talk podcast for design and development news.

The Sass Way is a great site. It contains tons of excellent user-submitted articles covering everything you'd ever want to know about or do with Sass. The site uses an open publishing model and relies on contributions from the community.